1. Field of the Invention
The present invention relates generally to a surfactant composition; to a concentrated pesticide-containing formulation prepared from said surfactant composition; and to a pesticide suspension or emulsion suitable for use in agriculture and related areas. More particularly, the invention relates to a surfactant composition comprising (a) a polyoxyalkylene alkyl or alkylaryl ether phosphate ester, such as a polyoxyethylene nonyl phenol phosphate ester, (b) a nonionic polyoxyalkylene alkyl amine, and (c) a material selected from the group consisting of nonionic polyoxyalkylated surfactants; polyhydric alcohol esters and polyoxyalkylene glycols; to a concentrated formulation comprising said surfactant composition, a pesticide and a suitable vehicle or diluent; and to an emulsion or suspension comprising a dispersion of said concentrated formulation in an aqueous medium.
2. Description of the Prior Art
Numerous synthetic, organic, biologically active materials are now commercially available and are useful for a wide variety of applications. These materials include insecticides, insect repellents, herbicides, fungicides, acaricides, nematocides, molluscicides, rodenticides, and the like. All of these materials are referred to herein by the generic term pesticides. In use, it is generally desirable to spray these materials onto a substrate (plant, animal, etc.) or area to be treated. Because of its availability, minimal cost, and lack of adverse environmental effects, it is preferred to apply these materials from an aqueous medium. However, many of these materials are insoluble in water and can be dissolved only in organic solvents. For this reason, such pesticides are conventionally, admixed with emulsifying agents and organic solvents to form concentrates which are subsequently added to water in small quantities to form emulsions. These concentrates are referred to herein as "emulsifiable concentrates". Other of these pesticides are not soluble either in water or in organic solvents. Concentrated formulations of these pesticides are generally prepared either as "wettable powders" or as "flowable formulations". In preparing a wettable powder from solid pesticide, the pesticide is finely ground and combined with an inert solid diluent such as kaolin, attapulgite clays, diatomaceous earth, etc., and a surfactant. When added to water in the desired quantity the wettable powder forms a stable suspension in the water. Wettable powders may also be prepared from a liquid pesticide by combining the liquid pesticide with a finely ground adsorbent carrier such as diatomaceous earth or a hydrated calcium silicate. Surfactants are added to these liquid pesticide/carrier blends so that the wettable powder will form a stable suspension when added to water. A flowable formulation is commonly a concentrated dispersion of a finely ground pesticide in a liquid medium. However, flowables can also be concentrated dispersions of liquid pesticides in a suitable dispersion medium. The dispersion medium used in these flowable formulations may be water, which is most commonly used, or an organic liquid, such as a low viscosity, paraffinic oil. The flowable formulations are stabilized by the addition of surfactants and thickening agents. Other ingredients which are conventionally employed in concentrated, pesticide-containing formulations include, for example, antifoam agents and freezing point depressants in flowable formulations and anti-caking agents in wettable powders. Another type of concentrated, pesticide-containing formulation is a flowable emulsion. This is a concentrated, stable emulsion prepared from an emulsifiable concentrate and water. Additives and surfactants such as those discussed above in connection with flowable formulations may be used in these emulsions. When added to water all of the flowable formulations form a stable suspension of the pesticide in the water. In addition to making it possible to apply the pesticides in an aqueous medium, use of these concentrated formulations also makes it easier to handle and market the pesticides.
Numerous types of emulsifying agents, surface active agents (surfactants), and combinations and blends of said agents have been suggested for use in preparing concentrated formulations of pesticides. However, the manner in which it is desired to use the pesticides in both farm and household applications places severe demands upon the emulsifiers and surfactants which are used in the preparation of these formulations. When an emulsifiable concentrate containing a pesticide, usually dissolved in a suitable organic solvent, and an emulsifier is added to water in the desired proportions, it is important that there be a rapid, in fact almost spontaneous, dispersion of the pesticide so that relatively little, if any, stirring or agitation is required. Furthermore, since the water to which the concentrate is added may vary widely in hardness, depending upon local conditions, it is necessary that the emulsifier be such that the desired rapid dispersion is affected, in the available water of given hardness. Also, particularly in recent years, it has become common practice to apply a combination of pesticides simultaneously meaning that a given emulsifier system must be useful with a variety of pesticides or at least be compatible with the other pesticide formulations with which it is to be combined. Finally, it is also becoming common practice to apply pesticides in combination with a liquid fertilizer--i.e., an aqueous solution of inorganic plant nutrients formulated to provide specific amounts of nitrogen, phosphorus and potash together with minor amounts of other trace elements. This is generally done by adding an emulsifiable concentrate of the pesticide to an aqueous based liquid fertilizer and preparing an emulsion of said pesticide directly in said liquid fertilizer instead of in standard water. In this application, the emulsifier used must be compatible with the liquid fertilizer and capable of forming a stable emulsion therewith.
Currently, when an emulsifiable concentrate designed for use in water is used in a liquid fertilizer, it is frequently necessary to use a compatibility agent to obtain a satisfactory dispersion. This is generally a surfactant which is added to the tank mix of liquid fertilizer prior to adding the emulsifiable concentrate. A compatibility agent may also be required when a concentrate designed for use in liquid fertilizers is used in water or when a combination of pesticide formulations is to be utilized. Although compatibility agents are useful, they are not preferred since their addition is not within the control of the manufacturer of the concentrated pesticide formulation, they must be carefully selected so as not to adversely affect the pesticide employed, and their use introduces a number of human and mechanical variables (addition, mixing, etc.) all of which can adversely affect pesticide performance if not carefully controlled.
The same requirements and problems discussed above in connection with emulsifiable concentrates also apply with respect to wettable powders and flowable formulations. It would, therefore, be desirable to have an emulsifier/surfactant composition that could be used in the preparation of concentrated, pesticide-containing formulations (emulsifiable concentrates, wettable powders, flowable formulations and flowable emulsions) which could be used to form stable emulsions or suspensions in a variety of naturally occurring waters, as well as in liquid fertilizers and in combination with other pesticide formulations without the need for an additional compatibility agent.